Manufacture of bead-form catalyst



Nov. 2, 1948. H, T, BROWN MANUFACTUR 0F BEAD-FORM CATALYST Filed May 24' 1946 ge/Cy wmf Brow/2J INVENTOR. y

A size.

Patented Nov. 2, 19,48

UNITED sTATss N l' v'2,453,084 i Poi-511mm? d afisslfosii o M-ANnraorUaE oFBEAnfsoMpoAaALYsm Henry Trueloeart'frcwn, Dallas?Texyassignore by` mesne assignments, to S'oconlyacnumrOili Companmlncorporat'eda FNew Yank, porationV mi.; New` York i app-umson-May24,194aseriarnagangers:

- be beadlike in forni, uniiorrnin` size,` andsuitable for use as adsorbent materiaLand/orsutablefor useascatalyticrnaterial for hydrocarbon conversion processes following furtherl neat-` treatment to activate the eelI particles. s A

It is known in the artt`o 'coagulatel a'stable alumina sol With an electrolytesuchasammonium hydroxideto produce a gel which, when dried` and activated by neat treatment, is a catalyst for hydrocarbon conversionA processes. Such acatai lyst isdescribed inU. SL Reissue PatentJ 22,196. It is also known that cogels of metastablehydrosols comprising variousloxides suchas mixtures `of a1umina and silica may be prepareclin beadlikefforrn.V The hydrosol is causedto set-:to the corresponding `liydrogel in spheroidal form assumed under the influenceiotsurface tensioxr against a fluid medium which `isnotrrniscible with the hydrosol. Such spheroidal'lcogels are described'in U. S. Patent 2,384,946; It has'i'been found that beadlike hydrogel particles ofalumina canbe formedbyinjecting stable alumina hyL drosol into a body of a iiuid medium Wliich'is not miscible with the hydrosol to form spheroidal droplets of hydrosol; The spheroidal particles flow by gravity through the immiscible uid to an t aqueous solution ofan electrolyte, such asa' Wealr solution of ammonia'in which the `lnydrosol'sets to alumina hydrogelf In the use of alumina gel beadsiitis liigllly'd'e#` sirable to employ particles of relatively/uniform One method consists of Washingoand drying the hydrogel beads andthenscreening'the beads to obtain the desired size. This rnetho'd involves additionalv handling `of 'tlfic-ibeadss undef-1 sirable attrition losses, and losses'by lorealzin'e,` thus increasing the-cost of manufacture. It'is an object of this inventionto'provide a mea-neef"V separating hydrogel beads of any desired size'frorn` hydrogel beads which are oversize andi/or untlri size; Another object of the inventionis toy recover oiisize hydrogel beads` immediately after beingformed whereby the oiisize beadsmaybe recycled tothe sol-producing step. Other objects of the invention Williappear hereinafter.` v

In one embodiment `of the invention; wlich is f droplets seti-t0 ny'droger ifea-csf ry me 4action pf l that the/only function e regulate trie-LA1 density ofitife "tremarerfluiagremmaueaiiynin the-drawing;

scribed finrdetail liereinbelow; amalgamated'f ulolishedvk at` a temperatureii Withiri the4 range of" fromabout to about 200 Rand-atta presesure suii'icientto*iireventranpreciablevaporization 10x; of' the-'acetic *acidi solution.` The pt ent-iziniq-'fi lion" f` is continuously [circulated *in\^contact?wit'lrftlef aluminum metaltol build una*concentrationfofi alumina hyd-resetcont'ainingfti'om to 8i' peri centi" of alumina. @The resulting'hydrosol isti-ienX cooled to a mperature-below about-86?. fan'flf'ypas'sedf were uydmgiatimstencrine process;l

'IP-lie hydrogelationY process; consistsA offjin'ecte" an* underlyin'goaqueous setting-agenti f1 isf-nietastable; thelbeaii's-set ringing@ passage-through theunediumeiresth eilylayerl` In' the caseofista-ble(l alumina YSol t-fisoappanntlf n thefsoliimnilsciblejlayer Y ist provide a'inediiu `lia-*vingtime` corr`er`ntir11ysi` ical' properties in#wineintheS streamer solfisrc'on4-1 Vertedintospneridal "droplets beforefpassing intofv 12h@n aqueous 'Setbinefkmediunr nrsfdesnaoiefte layer? with* respect" toA the'density of*4v the sol@ so? that the" beadzsrwlllf" pass-*rapidly intol the aqueous settingeagenti not sorapidlylasa to cause ydistortion"iv-lienA passing-jy through the ix'it'rface bettveeni the olfl layerfanidff 45" iffa small'fj amount ofi'Tl the setting agentjd'ses from' tlielowercrl settingfmediumiinto therupp'er" desirable-'incide Vcase 1 Y d particles. The time of passage may also be controlled by regulating the density and/or viscosity of the oil. The sol-immiscible medium should have such chemical composition as to not substantially decrease the surface tension in the droplets, thus permitting distortion before setting takesyplace;l n l A relatively!highsboiling kerosene, mineral seal oil, or a light gas `oil is suitable for use as the hydrosol-immiscible liquid. If desired, other oil miscible liquids of higher specific4 gravity, such as carbon tetrachloride, may be mixed with the hydrocarbons to raise the specific gravity ofthe hydrosol-immiscible liquid. The oil is superimposed on a body of liquid setting agent consisting of an aqueous solution of a suitable electrolyte, such as a weak solution of ammonia. For example, when preparing unpromoted alumina catalyst, the stable hydrosol may be converted to the hydrogel in this bottom liquid layer by the -use of an ammonium hydroxide solution having a pH of from about 6,. 5 to 8.0,., preferably about 7.3. The .pH of the vammonium hydroxide solution Iaifectstherate' of fgelation In general, I prefer to usev relatively rapid gelation rates in order that denitely formed beads of hydrogel will form in the time required for descent of the particles through the layer of settingagent.,

Iffa promoted alumina catalystis desired, an aqueous solution of an ammonium salt of the acid corresponding to the activating oxide may be used intheaqueous setting layer in the tower. For example, an aqueous solution of ammonium metavanadate may be used if it is desired to produce a vanadium oxide-activated alumina bead catalyst. Ammonium chromate and ammonium molybdate solutions may be used `to preparechromic oxide .and molybdic oxide-activated alumina bea-d catalyst.A On the other hand, an aqueous solution of these ammonium salts may be incorporated in the sol by rapid mixing therewith immediately preceding the time of `injection of the sol into the oil layer vin which type operation Ia separate aqueous setting agent is not required.

vThe .size of the globules of hydrosol formed in the oilris'vcontrolled bythe rate at which the hydrosol` flowsgthrough the orice of the injection nozzle,-on-;the dimensions of the nozzle and on the viscosity ofthe oil. The relative densities of the hydrosol and of the immiscible liquid, i. e., vthe oil, alsoaect the size of the particles. Thus, if the diiferential density is small the size of the svpheroidal particles ,will tend to be large. The use of moreA dense, concentrated hydrosols tends to increase thefdiierential density resulting in the for.- rnati'on of smaller beads.; In any case, the h3.- drogel particles formed from the hydroso-l are generallyof unequal size .and itis highly desirable toV classify.v the hydrogel particles from the hydrogelation step before drying in order to recover for final processing only the desired size particles.`

tionsof the tower progressively increases atlevels above theflevel of introduction of the liquid suspension. This tower may be shaped likean in,- Viertedz cone. AtthelointA of introduction ofthe liquid suspensionthe cross secti-onal area of a horizontal section of the tower is greater than `the cross sectional arcani vthe stream .and there-is an 4 initial decrease of the linear velocity of the stream as it enters the body of liquid in th-e classifier.

As the liquid rises in the classifier the velocity l progressively decreases .as a result of the increased cross sectional are-a of the tower. As a result of the initial decrease in velocity the oversize particles .ten-d to settle i'irst-and-may beseparately drawn off as a slurry from the bottom of the tower. Further decrease in the velocity of the stream as the liquid rises in the tower permits the settling .and stratification of the Iparticles of the I `ticles may be combined and filtered, andthe hydrogel particles so recovered m-ay be washed, If the hydrogel particles consist of alumina hydrogel, the washed, oisize hydrogel spheroidal particles may be crushed and slurried withlanl aqueous solution of a low molecular weight org-anic acid,` such .as acetic acid solution to repeptize If repeptization ofy the hydrogel tothe hydrosol. the alumina hydrogel is incomplete, the stream of suspended hydrogel may be recycled Vto the `peptizler tower to furnish make-up acetic acid. If repeptization is complete, the resulting'hydrosol may be recycled :to the hydr-ogelation step. The concentration of the acetic acid solution used for repeptizing the hydrogel is preferably within the range of from yabout 3 to 5 weight per cent and may be as high as 10 weight per cent.

If the particles consist of silicalhydrogel v or silica-alumina hydrogel, the crushed and slurried offsize hydrogel may be yreconverted to the hy' drosol by dissolving the hydrogel in an aqueous solution of an alleali, which can then be acidied to The hydrosol may be recycled 1 form the hydrosol. to thefdroplet-forming step.

The liquid suspension of intermediate size catalyst they are heat-treated at a temperature of 4from about 800F. to labout 950 F. to activatethe alumina gel beads and to decompose and remove;A therefrom the ammonium salt of the acid used as the peptizing agent.

-The degree of separation and the range of` particle size `in the fractions segregated at different levels in the classifier will depend on the distribution of particle size in the suspension, on

the linear velocity of the stream at the point of v introduction to the classifier tower, and on the `differential linear velocity of the stream in the tower as aiected by the angle of the cone. Thus; if it is desired to remove only the finest particles and extremely oversize particles as separate fractions; an inverted cone-shaped chamber having a j level above the zone of segregation of the inter-4 mediate size hydrogel particles thereby producing higher stream velocities in the upper section` of the classifier and facilitating removal ,of the attacca undersize fparticles. ,It `will be A:obvious to :those ski-lled inxthe art that the clasiiicationfsof Tthe hydrogel particles having f diierent diameters will :take placefas a rresult. of ancequilibriumso-r balance -between i,their `several terminal .velocities as c'alculatedfrom iStoke'sflaw and the progressivelyf` decreasing velocity. of ithe` sus-pending@ liquid resulting :from the.` shape of the tower.

'The Vinventionmay .bebetter understood. byrei erence to the` drawing whereinithefpreparation of aluminabeads is diagramin'atically illustrated .and described, --Reierring now to the gure-peptizer towerA .IOM-is loosely .packed with amalgamated aluminum` metal oi relativelyhigh purity,-prefer ablycontaining-'notmore than 0.10 `per cent copper, The packing .in tower I0 may bewdisposed therein'as a continuousbed or the` aluminum metalmay be containedin` a series of` separate trays. dilute acetic acid solution from line il isipassed bymeans offpump I2 in line l3to heater I4 where lthe solution .is raisedto a temperature somewhatabove 150F.,:preferably to 'about 175 F. f'lhe `hot solution passes from heater Ill through line l5 and is introduced totower Il) at apoint somewhat above .thebottom of the tower. Asa `solution passesV upward through tower It! in contact Vwith the amalgamated aluminum a hyM drosol of alumina is formed. Aluminum is consumedand hydrogen is formed. Metallic mercuryyfreed` from theamalgated metal, is withl drawnaintermittently from tower `I0 through line IL Apart -cirthe'mercury in a nely divided state is usuallycarried along in suspension in the solutionfwhichpasses overhead through line Il to defoamer .18. Finely divided particles of aluminum e up the `foamgin the liquid and consists of a vessel packed with a material which will furnish a large surface area such as glass `wo'olorother suitable material inert 'to the acidic hydrosol. The defoamermayalsolbe provided with such inert material arranged as a iilter medium to remove small.

suspended lparticles of aluminum and mercury fromithe circulating liquid. The liquid product passesiromgdefoamer i8 through line I9 to hydrogen 'release tower 20 when-ce hydrogen is vented `from..theliquid in tower through line 2l, The ,liquid product passes from towerii through line .22 which connects with line I3 and the` acidic liquid is recirculated through tower .t0 to increase the concentration of alumina hydrosol to within 4the rangeof from about 4 per cent to` about4 8 .per .cent by weight of alumina as-described hereinabove. When the concentration of hydrosol in line 22 is suf-ciently high apart lof thehydrosol is withdrawn therefrom through line 23..which leads tocooler 2eA wherein the tempera p ture of the hydrosol is lowered to aternperature below.about80 F. The.` hydrosol passes from cooler 24 through line 25 to centrifuge 2t for the separationy of the last traces of suspended metallic aluminum andmercury. From centrifuge `2t-the claried hydrosol is vpassed `throueh `liney 2l .by means-ofopurnpl to spray nozzle 29 which is immersed in the upper liquid layer, that is, the oildayerin hydrogelation tower 30.

.ljlydrogelationtovreiz 30 .contains two .bodies. of`

liquidfifconsisting otn=aci1iquidyhaving a spcifie gravity somewhat :less tirant .1.00 :withcwhichzithe hydrosolis s'immisciblessuperimposed fennel-liquid setting medium or'ihydrogelationf `imediunr conn sisting of 'at solutionw'of-liammzoniasfy infwater 'toxftin an alcohol-water solution. Thespecifc':gravlties of the two bod-ies of ;liq.uidszvmayi:be ,made more neary Y equahbyiraising ,the gravityoilith'eisuper-Y natantpredominaiitly `oil phase. and! orzlbyfllowering the specific'V gravity. of` the ,-hydrogelation ".me-

dium; ItV is `lnecessary,.,that, .ther density of: fthe hydrosol be suiiicientlyvgreaten than :the densityxof the Vgelatin-n2.medium: to iminimize4 :the: hindrance to passagefof lthe hydrosol :particles tthrouglrithe interfacefbetweenlthe two liquid media. flteduc-` tion V'of'V interfaeialftension betweenfthe two-.liquid media :in tower-"38 i also Afacilitates the massage-:lof the hydrosol .particles through :the .rin-terface. Hence, af proper choice.` offfblendinig? liquidaeither for the oil in the supernatant layer` or..for:.:the

` predominantly aqueous jlower.zleyerl v:is:A desirable.

Carbon tetrachloridelis .a suitableblending liqui'dfor the.hydrocarbonvoillayer. .f'I'hevusenof ethyl falcohohas a .ifblendingililiquid for-,zithe aqueous .layerxlis taught, and "claimed in", tliieneo pending :application `entitled Hydrogelation process, *Serial -l\lumlo.er'y 750,171, :filed May 2.3,.`

p of- `the `solution in towersmi 'and 'I0 :in forder' to produce a combined oil plus` solution -hydrostatic head intowerf slightly gre'aterf'than the hydro-l static headproducedby the columni of--solutiorrfin` tower 40. Hydrosol is then introducedtonozzle` 29 under sufficientpressureutolform partie-lfes'rof h ydrosol of the approximate" desired'. size `which fall lthrough the supernatanto-il layer asfsphe` rcidal particles. The particles `pass 5throughlrinterface 314 into thei ammonia solution: andi setlto spheroidal `hfy'drogel particles-astheyiowdown-l ward under itheiniiuence of gravity. The-hydro'- gelparticles pass tobaseof thetower whereithey are `picked l up by 'the stream `of Asetting isollution'l flowing in linesf el; 'andifS'L` Thevparticlesare 'eari ricd at a constant velocityfintofclassieridland through nozzle 4I' l'bythe streami of setting solution `to a level` somewhat above thebottom o'f'the" classier. At thelloveliot nozzle'ii theiforossi sectional area ot a.horizontalsectionbfthe -tower is greater thanithecrosshsectional ar-eafof the stream flowingilfrordithei'nozzle. i

The i llinear 1 .velocitywof the stream `lbecornes progressively'.i ilower as thedliquidirisesiiin L classi-` ei'fri. :vAt no levelfiniit'heicl-assierlisthellinear velocity of the `strearnfsuiii'cient .#to L`overcome fthe normal settling vivelocity, ithat` is, irtoles? J-law` terminali velocity; vof :the'u'ov-ersize spheroid'al para ticles. Hence, itheseeparticles seti-,lento aslevelsbelow n'ozzleilii andareiwi-thdrawn from fclass'ifier @was a slurry ithroughilinesv-e andfevrbynreansl oi ipump flti. xAs fthefstreamrises" in, the iclaseiier the'ili'near; velocity-1progressively: decreasesrvtoma value equal;.1to the' normaly `settlingfilelocityloflthe intermediateu size spheroidal iparticlfes. "TSubs`tan'- tial -equilibriumiofxthe :settling tendencylrot these desired size; 1ra-ngen:particles..y versus" thewtendency tombe :carriedjinisuspensioniresurltsn andzithe' desired `size irangeipeafticl'es .tendfito segregatelilihese particles? :collect: finiA trayi; 14,8. Ehi-desired; tra sim may takeith'e'.iformzronan.;annulanstrougndocated around ithefjperiphery.; oiiithezinnerfsurfeoe mitiche classier. Such an annular trough may be slightly inclined 'in order to provide free flow of the slurried particles to drawol line 49 or the annular trough may be provided with a multiplicity of drawoif lines which are manifolded to mainA drawof line de.

The slurry of particles passes by gravity flow through line lli) to settler 50 whence the settled hydrogel spheroidal particles pass via line l to drier 52. If desired, the hydrogel beads may be subjected to a washing step (not shown in the drawing) before being dried. rPhe hydrogel spheres are dried at a temperature of about 212 F. in drier 52, and the dried bead-form gel particles are passed through product line 53 to the heat treatment step (not shown) where they are subjected to a temperature within the range of from about 800o li'. to about 950 F. to decompose residual adsorbed acetates and to activate the particles.

The stream of solution containing undersize hydrogel particles continues in upward flow in tower 40 and overflows through line t0 which connects with line iii and the combined streams from lines d5 and Gil are passed to a rotary vacuum filter 6l of the Oliver type, preferably equipped with a repulper, for separation of the hydrogel from the setting solution. The setting solution is recycled from filter iito line 36 through lines 62 and Setting solution from settler 5i) is recycled through line Si which joins line tit, When the setting agent becomes depleted with respect to dissolved ammonia, makeup ammonia may be added directly to the aqueous layer in' tower 3G through line 65 either as ammonia gas or as concentrated ammonium hydroxide. Make-up setting agent may be introduced to line it through line E55.

Hydrogel which is recovered from filter 6l passes by gravity to mixing tank 'ID which is equipped with mixing device lll. An aqueous solution of acetic acid of from 1 to 5 per cent concentration from line 'i2 is added to mixing tank 10 at a temperature with the range of from about 150 F. to about 200 F. Thorough mixing of hydrogel with the hot acetic acid solution results in repeptization of the hydrogel to hydrosol which may be recycled through lines 'i3 and 'ld to cooler 'I5 wherein the temperature is lowered to 80 F. or less. The cooled hydrosol is p-assed from cooler 'I5 through line 'i6 to line 27. If desired, the acetic acid containing any non-peptized hydrogel may-bev recycled to line i3 through lines 13, 11, and li, and thereby furnish make-up acid for the peptizing step of the process.

VVarious modifications may be made in the apparatus and method of carrying out my process without departing fromthe spirit of the invention. For example, the ilow of peptizing agent in tower l0 may be directed downward instead of upward or the now may be directed through a horizontal tank type reactor. Instead of using a single vessel of conical shape to separate the hydrogel spheres, use may be made of a classication zone consisting of a series of two or more vessels of such shape and size that a liquid suspension of hydrogel particles will deposit oversize spheres in the rst vessel and allow nes and small spheres to be carried out of the last vessel of the series. By means of a series of such vessels any number of intermediate sized fractions may be separated as settled segregated slurries of spherodal particles from sections of the stream of liquid suspension where the velocity of the stream is intermediate the initial velocity as the stream enters the lirst tower and the final overilow velocity from the last tower. These vessels need not be cone-shaped. For example, the desired decrease in stream velocity as the suspending liquid rises in the classifier may be made intermittent instead of continuous by separating successive uniform increases in diameter ofthe classier by sections, the walls of which are per-A pendicular, that is, by alternating inverted conical frustrums with cylindrical sections.

The process is also applicable to the classification of bead-form hydrogel particles of oxides other than alumina. Thus, silica hydrogel. silicaalumina hydrogel, and hydrogels of other mixed oxides may be classified by my process. Oversize and undersize hydrogel particles may be segregated, thus saving the expense of large scale equipment for drying, screening, and handling thev gel product. The process is particularly advantageous for separating undersize and oversize beads of oxides. the hydrogels of which' are susceptible to repeptization in the hydrogel state but which as gels are diicult of or impossible of repeptization.

rihe process is applicable to the classication of spherodal gel particles which can be formed from hydrosols of normally solid inorganic oxides, more specifically, solid amphoteric oxides. Such hydrosols may be formed by building up colloidal particles from ions, as, for example, the formation of silicc acid sol by the addition of a solution of sodium silicate to a mineral acid. The hydrosol of the inorganic oxide may also be formed by breaking down an oxide or a gel structure thereof to colloidal size by means of peptization, as, for example, by peptizing hydrated alumina by means of acetic acid. The term inherent capa-city of the hydrosol to set to a hydrogel as used in the specification and claims refers to that property of the hydrosol which is manitested by a capacity to change from a relatively low viscosity to a relatively high viscosity either by the influence of time and/ or temperature or by the addition of an agent to the hydrosol which causes a change in the hydrogen ion concentra` tion in the hydrosol. 1

1n the case of silica-alumina beads containing predominantly silica gel the offsize fractions may be recovered by pulping or crushing the beads of hydrogel and by treating the resulting slurry with an aqueous caustic solution `such as sodium hydroxide. This results in a solution of sodium silicate and sodium aluminate which 'may be reconverted into beads by mixing continuously with sulfuric acid in the correct proportion and injecting into the oil layer of the hydrogelation process. This recovery before drying of the hydrogel is particularly advantageous because the freshly formed silica hydrogel is readily soluble in this state while it becomes less readily Lsoluble after drying and after being activated by heating to a h1' gh temperature.

I claim: i

1. In a continuous process-for the manufacture solid inorganic oxide characterized by an inherent capacity to set to a hydrogel, (2) continuously introducing said hydrosol into a body of a liquid iii which said hydrosol is immiscible to form a multiplicity of spheroidalparticles of different sizes, (3) continuously Iconverting said particles of hydrosol to particles of hydrogel, (4) continu 9. ously classifying` the` hydrogeluparticles of step 3 to separate undersize and oversize particles of hydrbgelfrom hydrogel particles of the size desired, continuously reconverting the undersize and oversize hydrogel particlesoi step 4 to hydrosol, (6) Jcontinuously recycling the hydrosol ofetep 5 to step 2, and (7)V drying the hydrogel particles of thedesired size recovered from'stepu.

2l In a continuous"processforthe manufacture ofispheroidal particles of alumina of -afdesird size range having adsorbent and catalytic properties the steps which comprise (1) continuously forming a hydrosol of alumina, (2) continuously introducing said hydrosol into a body of a liquid with which said hydrosol is immiscible to form a multiplicity of spheroidal particles of different sizes, (3) continuously converting the spheroidal particles of hydrosol of step 2 to spheroidal particles of hydrogel, (4) continuously separating the undersize and oversize spheroidal particles of hydrogel of step 3 from the spheroidal particles of hydrogel of the desired size range, (5) continuously reconverting to hydrosol state the undersize and oversize spheroidal particles of step 4, (6) recycling the hydrosol of step 5 to step 2,

and (7) continuously drying the desired size range spheroidal particles of hydrogel recovered from step 4.

3. The process as described in claim 2 wherein separation of offsize spheroidal particles of hydrogel from spheroidal hydrogel particles of the desired size range is accomplished by continuously introducing at a constant velocity a stream consisting of a liquid supsension of the said particles into the lower part of a tower, the cross sectional areas of horizontal sections of which tower at the level of introduction of said stream and at levels above the point of introduction of said stream are successively greater than the cross sectional area of said stream at the level of introduction of said stream, continuously passing said stream upward in said tower to effect `a reduction in the linear velocity of said stream at said levels of greater cross sectional area whereby oversize particles and desirable size particles tend to settle from said suspension and concentrate` in successive separate layers and undersize particles are carried overhead in suspension in said liquid stream, and continuously trapping out from said separate layers separate streams of liquid slurries of said oversize particles and the desired size range particles.

4. The process as described in claim 2 wherein the undersize and oversize hydrogel particles are reconverted to a hydrosol of alumina by treating said particles with an aqueous solution containing from about 3 per cent to about 10 per cent by weight of acetic acid.

5. The process as described in claim 2 wherein separation of ofsize spheroidal hydrogel particles from the desired size ra-nge of spheroidal hydrogel particles is accomplished by continuously intoducing at constant linear velocity a stream consisting of a liquid suspension of said particles at a level above the apex of an inverted coneshaped tower, continuously passing said stream upwardly in said tower at a constantly decreasing linear velocity in said tower whereby the oversize and desired size range particles of said suspension tend to settle and form separate layers of said oversize and desired size range particles, continuously passing said stream containing undersize particles suspended therein from said tower, and continuously removing from said ously forming a hydrosol of at least one normally solid inorganic voxide `characterized by an inherent capacityfpto 4set vtoa` hydrogel,` (2) f `continuously introducing said hydrosol,;into abodyi of` a liquid in which said hydrosol is immiscible to form a multiplicity of spheroidal particles of different sizes, (3) continuously converting said particles of hydrosol to particles of hydrogel, (4) continuously passing a liquid suspension of the hydrogelparticles upwardly through a classiiication zone consisting of at least one tower wherein the velocity of liquid progressively decreases, (5) regulating the discharge liquid velocity from said classication zone so that undersize hydrogel particles are discharged overhead-therefrom, (6) continuously withdrawing from the high liquid velocity section of the classification zone a slurry of oversize hydrogel particles, (7) continuously withdrawing from said classiiiication zone at at least one section of intermediate ves locity hydrogel particles of the desired size range as a slurry of settled, segregated particles, (8) continuously reconverting the undersize particles and oversize particles to hydrosol, (9) continuously recycling the hydrosol formed in step 8 to step 2, and (10) recovering and drying the desired size range particles of step 7 of the process.

7. In a continuous process for the manufacture of` inorganic oxide spheroidal particles of a desired size range having adsorbent and catalytic properties the steps which comprise (1) continuously forming a hydrosol of at least one normally solid inorganic oxide characterized by an inherent capacity to form a gellable hydrosol, the hydrogel of which is reconvertible to the hydrosol state, (2) continuously introducing said hydrosol into a body of a liquid with which said hydrosol is immiscible to form a multiplicity of spheroidalparticles of hydrosol, (3) continuously suspending said hydrosol particles in a gelation medium and converting said `particles to suspended spheroidal particles of hydrogel, (4) introducing a liquid suspension of the hydrogel at a point above the bottom of a tower of a shape such that the cross sectional areas of horizontal sections of said tower at the level of the pointof introduction and at at least one higher level are progressively greater than the cross-sectional area of the liquid stream at said point of introduction whereby oversize particles are caused to settle and segregate below said point of introduction of said stream, (5) continuouslypassing said stream of suspended particles upwardly in said tower whereby the linear velocity of said stream is progressively decreased, hydrogel particles of the desired size range are caused to settle and segregate at a level above said point of introduction of said stream and undersize hydrogel particles are carried upward in suspension and from said tower, (6) continuously passing as a liquid slurry the oversize hydrogel particles of step 4 and the suspension of undersize particles of step 5 to and through a hydrogel recovery zone for the separation of hydrogel from the suspending liquid, (7) recycling the liquid separated in step 6` to step 3, (8) continuously converting the hydrogel recovered in step 7 to the corresponding hydrosol of said inorganic oxide, (9) passing the segregated desired size range of 11 12 hydrogel particles of step 5 as aslurry from said A i tower to a settling zone, (10) recycling the liquid UNITED STATES PATENTS separated in step 9 to step 3, and (11) recovering Number Name Dette` i and drying the separated hydrogel particles of 1,281,371 Hitchcock Oct. 15, 1913 step 9. v 5 1,319,771 Hitchcock Oct. 28, 1919 HENRY TRUEHEART BROWN. 2,203,825 Komarewsky June 11, 1940 2,371,087 Webb et 2,1. Mar. 6, 1945 REFERENCES CITED 2,371,237 Heard et al Mar. 13,1945 The following references are of record in the 2,384,946 Mal'lslc Sept" 18: 1945 me of thisfpatent: 10 2,387,596 Marisic Oct, 23, 1945 

